1. Field of the Invention
The present invention relates to a side airbag unit for a vehicle, which is constructed so that a strap is locked when an airbag module is assembled with a seat frame.
2. Description of Related Art
Generally, an airbag system is a safety device which includes an impact sensor, an airbag module and an airbag control unit, and causes an airbag cushion received in the airbag module to be expanded by gas in the event of a collision, thus protecting a driver or a passenger from shocks.
The airbag system was mainly developed to provide safety in the case of a head-on collision between vehicles. Recently, a side airbag has been developed to provide safety in the case of a side collision or a vehicle rolling over.
After an inflator received in the airbag module generates gas as a result of an explosion, it takes about 5 ms to inject the gas into the airbag cushion. It takes about 30 ms for the airbag cushion to expand.
When a driver or passenger moves in the direction where an object with which impact can be made is located, the expanded airbag cushion absorbs the shock, so that injuries are reduced. It generally takes about 40 to 60 ms to absorb the shock after a collision.
Finally, the driver or passenger returns to his or her original position by the restorative force of the airbag cushion, and the gas is slowly discharged from the airbag cushion. It usually takes about 120 to 135 ms to perform this process.
Especially, since a side airbag is mounted to a side of a seat so that the airbag module is located between the seat and a door or between a driver's seat and a passenger seat, the flank or head of a person sitting in the seat can be protected when the airbag cushion is deployed.
The side airbag is provided with a strap which restrains the airbag cushion such that it is always deployed to a predetermined length at a predetermined position when the airbag cushion folded in the airbag module is deployed. Here, one end of the strap is secured to a side portion of the airbag cushion.
However, since the other end of the strap is secured to a side portion of the seat, an additional operation of attaching the other end of the strap to the seat is required when the airbag module is mounted to a side of the seat, so that the number of assembling processes and an assembling period are undesirably increased.
Further, when the side airbag is placed between the driver's seat and the passenger seat, a lateral force acts on the airbag cushion which is deployed in the longitudinal direction of a vehicle body, and the airbag cushion does not sufficiently support passengers, so that they may collide with each other secondarily.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.